#include "studio.h"

int main(){
    int a = 1;
    int b = 2;
    int a = a ^ b;
    int b = a ^ b;
    int a = a ^ b;
    printf("a=%d,b=%d",a,b);
    // one feature
    // two feature
    // three feature
    // four feature 1
    return 0;
}
